The truth about THAC0

[diaglo]

2. OD&D certainly (and I think AD&D 1e) didn't formally have THAC0 originally - it was all table based (like most table top wargames of that era, in fact). Cross reference your class & level against target AC to give you a number you had to beat on a d20.

as others have or will point out. the monster index in the back of the 1edADnD DMG (1979 revised)

had ThAC0 sorta.

but OD&D we have charts and we use weapon vs armor type. edit: with the intro of Supplement I greyhawk

 

[Vraille Darkfang]

I could argue that a system with AC ranging from -60 to -40 is as easy the current system, in a way similar to the thread starter, but whats the point .. ?

What system is this? AD&D capped out at -10 AC. Made high level play (I was involved in several) into rifts. "Rolled a 3, that's a hit".

And, it didn't matter how nasty the monster was, it alwasy had an AC no better than -10. A high level fighter (and some clerics) would get to the point they hit on a 2 or better (only because a 1 always missed.

The fact 3rd doesn't have an AC cap helps balence out high level play (not actually refencing the Epic Book here), thus I find it much easier to challenge high level parties in 4rd as opposed to 2nd (and I've run 18th level+ in both editons).

 

[Ravellion]

The bonuses are not, but the DCs are arbitrary. The fact that you aren't looking them up makes them arbitrary. Even if you did look them up, where is the formula set forth by the designers to populate the chart? Note that I don't think that arbitrary is a bad word.

It usually is 10+half the creature's hit die + Con or Cha modifier.

Did I just ruin the game for you ?

Rav

 

[dcas]

The THAC0 (2e) system may be less intuitive than the BAB (3e) system; however, there were generally fewer modifiers in 2e than there are in 3e.

I think percentile-based systems are the most intuitive, myself.

 

[Janx]

1e's table look-ups were slow. That's why it sucked. Once folks realized you could reduce it to simple formula, things got better. The result, was 2e's THAC0

When WotC first bought TSR, the first thing Adkision pimped in a Dragon editorial was reversing the AC math, so the numbers went up. Gee, where do you think 3e came from...

In fact, technically, your BAB is really THAC0, which still stands for "To-Hit Armor Class 0"


And in the old 2e days (which I played from '90 to 2000), we ALWAYS told the players what the AC was. The nature of the formula implied that telling the players the numbers made the combat faster.

When the rules day, "subtract the AC from your THAC0, that's what you need to roll or higher to hit" it pretty much implies you need to know the AC before you roll the die. Not doing so (on the DM's part) is what slowed combat down, for the sake of purported realism. No wonder so many people complained about 2e, with DM's running their game with secret ACs....combat would have to suck.

Janx

 

[TerraDave]

There were two issues:

The first was mathematical. People add much faster and more accurately than they subtract. When you have subtraction of negative numbers, things get hairy for the less mathematically competent amongst us.

For a fighter with a THAC0 of 14 to strike a monster of AC -2, the fighter had to roll a 16 or higher (14 - (-2) = 16).

I had someone in my old group who I had to explain how THAC0 worked every single session. This was a problem.

The second was due to inconsistency between whether rolling high was good (saves and attack rolls) or whether rolling low was good (attribute and proficiency checks).

Jonathan Tweet notes that the attribute/proficiency system (rolling low) also worked very badly for opposed checks... it ended up being who rolled higher without rolling higher than their skill! The unified d20+modifiers check of 3e fixed that problem very nicely.

Cheers!

All those THACO calculations, and teaching all those people THACO...and thinking "this is simple enough, why aren't they learning it faster"...what a waste.

Merric covers the main issues...and if THACO was bad, those opposed rolls where a mess (and yes, you could combine them! who could roll lowest to hit a target AC, or something like that)

 

[diaglo]

1e's table look-ups were slow. That's why it sucked. Once folks realized you could reduce it to simple formula, things got better.

in ye olde dayes. it just required the player to roll the d20. add or subtract their modifiers and tell the score. it still does.

the referee or DM will tell you if you hit or not.

 

[TerraDave]

as others have or will point out. the monster index in the back of the 1edADnD DMG (1979 revised)

had ThAC0 sorta.

but OD&D we have charts and we use weapon vs armor type. edit: with the intro of Supplement I greyhawk

I remember it being introduced in Dragon and various mods (where NPCs would have a thaco) before being mainstreamed in the 2nd edition players handbook.

And for OD&D wasn't it a chart for things like Troll vs. Ent ...maybe that was chainmail?

 

[francisca]

It usually is 10+half the creature's hit die + Con or Cha modifier.

Did I just ruin the game for you ?

Rav

Nope. You'll have to try harder next time.

1e's table look-ups were slow. That's why it sucked.

Then I and everyone else I've played with must have a penchant for looking up things on a chart in a big hurry, because it's not slow to me. It's certainly not slower than combat in 3e, in my experience.

 

[Quasqueton]

It seems to me there is far more arbitrary stuff in 3e than people realize/admit/think about. And I'm glad for it, for if 3e was *all* about formulas, I would never have played it. (Not that there isn't a ton of formula manipulation to be had.)

You haven't really paid attention to the rules, have you? If having numbers based on formulas would bother you, I'd suggest you stay blissfully ignorant of the details. For your own good.

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Thac0 was a manual shift transmission, and BAB/reverse AC is an automatic shift transmission. Manual shift is more difficult to learn, but once you get the hang of it, you can drive just fine. You may grind a gear every once in a while, but it's perfectly drivable. Automatic transmission is easier to learn, and is a bit easier to drive. But having something easier/better doesn't mean the older method is/was *bad*.

Quasqueton